Re: [Phonopy-users] Need help to used modulation command

[Naveena P.S. <nav...@gm...>]

Hi,

I need help to perform atomic modulation with a specific q-point
(pre-processing after DFPT calculation using QE)  using phonopy. MODULATION
= (command). How to perform this?

if you need any additional input, let me know.

with regards
Naveena

On Fri, Feb 13, 2026 at 4:38 AM Atsushi Togo <atz...@gm...> wrote:

> Hi,
>
> Information is too little to see the issue. So it is difficult to answer.
>
> > I found your youtube videos
>
> I think those are not my youtube videos.
>
> Togo
>
>
> On Fri, Feb 13, 2026 at 1:22 AM Naveena P.Sivam <nav...@gm...>
> wrote:
>
>> Hello
>> I am trying to do atomic modulation (atomic displacement) with respect to
>> the normal mode at the specific q point. I tried to use this command line:
>> phonopy --qe --modulation 2 2 1, 0.000000000   0.433012702   0.000000000
>> 1 0.03 0 -c TiS2_primitive_scf.in --dim 2 2 1 -v.
>>
>> But it provides error like this:
>>
>> phonopy --qe --modulation 2 2 1, 0.000000000   0.433012702   0.000000000
>> 1 0.03 0 -c TiS2_primitive_scf.in --dim 2 2 1 -v
>>         _
>>   _ __ | |__   ___  _ __   ___   _ __  _   _
>>  | '_ \| '_ \ / _ \| '_ \ / _ \ | '_ \| | | |
>>  | |_) | | | | (_) | | | | (_) || |_) | |_| |
>>  | .__/|_| |_|\___/|_| |_|\___(_) .__/ \__, |
>>  |_|                            |_|    |___/
>>                                       2.47.1
>>
>> -------------------------[time 2026-02-06
>> 16:53:41]-------------------------
>> Compiled with OpenMP support (max 8 threads).
>> Python version 3.11.11
>> Spglib version 2.7.0
>>
>> Calculator interface: qe
>> Crystal structure was read from "TiS2_primitive_scf.in".
>> Unit of length: au
>> Modulation mode
>> Settings:
>>   Supercell: [2 2 1]
>> Spacegroup: P-3m1 (164)
>> Number of symmetry operations in supercell: 48
>> ------------------------------ primitive cell
>> ------------------------------
>> Lattice vectors:
>>   a    6.460973493253429    0.000000000000000    0.000000000000000
>>   b   -3.230486746626715    5.595367178253872    0.000000000000000
>>   c    0.000000000000000    0.000000000000000   34.015070466894429
>> Atomic positions (fractional):
>>    *1 Ti  0.00000000000000  0.00000000000000  0.50000000000000  47.867
>>    *2 S   0.66666700000000  0.33333300000000  0.57891028530000  32.065
>>     3 S   0.33333300000000  0.66666700000000  0.42108971470000  32.065
>> -------------------------------- unit cell
>> ---------------------------------
>> Lattice vectors:
>>   a    6.460973493253429    0.000000000000000    0.000000000000000
>>   b   -3.230486746626715    5.595367178253872    0.000000000000000
>>   c    0.000000000000000    0.000000000000000   34.015070466894429
>> Atomic positions (fractional):
>>    *1 Ti  0.00000000000000  0.00000000000000  0.50000000000000  47.867 > 1
>>    *2 S   0.66666700000000  0.33333300000000  0.57891028530000  32.065 > 2
>>     3 S   0.33333300000000  0.66666700000000  0.42108971470000  32.065 > 3
>> -------------------------------- super cell
>> --------------------------------
>> Lattice vectors:
>>   a   12.921946986506859    0.000000000000000    0.000000000000000
>>   b   -6.460973493253429   11.190734356507743    0.000000000000000
>>   c    0.000000000000000    0.000000000000000   34.015070466894429
>> Atomic positions (fractional):
>>    *1 Ti  0.00000000000000  0.00000000000000  0.50000000000000  47.867 > 1
>>     2 Ti  0.50000000000000  0.00000000000000  0.50000000000000  47.867 > 1
>>     3 Ti  0.00000000000000  0.50000000000000  0.50000000000000  47.867 > 1
>>     4 Ti  0.50000000000000  0.50000000000000  0.50000000000000  47.867 > 1
>>    *5 S   0.33333350000000  0.16666650000000  0.57891028530000  32.065 > 2
>>     6 S   0.83333350000000  0.16666650000000  0.57891028530000  32.065 > 2
>>     7 S   0.33333350000000  0.66666650000000  0.57891028530000  32.065 > 2
>>     8 S   0.83333350000000  0.66666650000000  0.57891028530000  32.065 > 2
>>     9 S   0.16666650000000  0.33333350000000  0.42108971470000  32.065 > 3
>>    10 S   0.66666650000000  0.33333350000000  0.42108971470000  32.065 > 3
>>    11 S   0.16666650000000  0.83333350000000  0.42108971470000  32.065 > 3
>>    12 S   0.66666650000000  0.83333350000000  0.42108971470000  32.065 > 3
>>
>> ----------------------------------------------------------------------------
>>   ___ _ __ _ __ ___  _ __
>>  / _ \ '__| '__/ _ \| '__|
>> |  __/ |  | | | (_) | |
>>  \___|_|  |_|  \___/|_|.
>>
>> Also, it creates modulation.conf which contains:
>> DIM = 2 2 1
>> MODULATION = 2 2 1, 0 0.433012702 0 1 0.03 0.
>>
>> Also, I found this idea from:
>> https://phonopy.github.io/phonopy/setting-tags.html.
>>
>> Just today I started to use this package and I found your youtube videos
>> discussing how to use phonopy with qe. So I thought I could ask for some
>> help. kindly help me if you have any ideas.
>>
>> with regards
>> Naveena P.
>> _______________________________________________
>> Phonopy-users mailing list
>> Pho...@li...
>> https://lists.sourceforge.net/lists/listinfo/phonopy-users
>>
>
>
> --
> Atsushi Togo
> _______________________________________________
> Phonopy-users mailing list
> Pho...@li...
> https://lists.sourceforge.net/lists/listinfo/phonopy-users
>